Jan. 26, 2011 -- Childhood leukemia and brain cancer are on the rise, and exposure to chemicals in our environment such as chlorinated solvents and the head lice treatment lindane may be partially to blame, according to experts speaking at a conference call sponsored by Safer Chemicals, Healthy Families.

The group is seeking to overhaul the 1976 Toxic Substances Control Act (TSCA), but not everyone in the scientific community agrees that chemical exposure is connected to the uptick in childhood cancers. Some suggest that improvements in diagnosing childhood cancers may also have a role.

"There are a number of chemical exposures for which the evidence is strong, including leukemia and brain cancer," said Richard Clapp, DSc, MPH, a professor emeritus of environmental health at Boston University School of Public Health, during the teleconference.

"Unequivocally the rates of these cancers have been going up for the last 20 years or more with about a 1% increase per year," Clapp says. "It is clear that at least one complement of the cause is environmental chemical exposure. Certainly a portion [of childhood cancers] can be traced back to damage done at the cellular level from chemicals that are carcinogens."

For example, he says, chlorinated solvents, which are used in many household products like paints, adhesives and spot removers, are strongly associated with childhood leukemia. He cites cancer clusters in Tom's River, N.J. and Wooster, Mass., where prenatal exposure to these solvents have been linked to leukemia. Such epidemiological studies do not show causation. Instead, they show that this risk factor is associated with a higher risk for developing childhood leukemia.

Clapp also says there is a growing body of evidence linking lindane to childhood brain cancers.

Exposure to Toxic Chemicals

Sean Palfrey, MD, a professor of clinical pediatrics and public health at Boston University, says that chemical exposures can be passed down, much like genes.

"We can eat them or drink them and they can get into our gastrointestinal tracts or we can breathe them in, touch them, and absorb them through skin and they can spread specifically to organs that they are toxic to," he says. "They may not harm the first organ, but they may harm the blood cells related to leukemia and brain cells related to brain cancer."

Our bodies have no idea how to detoxify these man-made chemicals or prevent them from being absorbed, he says. "We store them so when a woman gets pregnant, those stored chemicals may be released and circulate into the fetal blood and breast milk. This is a multigenerational problem so if mom is exposed, she can expose the fetus and baby."

Exposure to any of these chemicals does not mean a person or their offspring will develop cancer. "My grandchildren as well as my children have in their lungs and bodies substances which might be able to cause cancer, but probably won't because this is a relatively infrequent thing," he says.

It's more than the exposure that is linked to cancer risk. "It is timing, genetics, the way it builds up, and where it is stored," Palfrey says. "All of these things add together to make it harmful."

Tips for Cutting Exposure to Chemicals

There are steps we can take today to help limit our exposures to these pesticides and toxins, he says.

"Wash your produce, eat organic fruits and vegetables, and try not to use pesticides in your home," he says. "Don't smoke cigarettes, and ask the doctor if a CT scan or X-ray is really necessary for your children, and take care when renovating your house, which may stir up asbestos or lead."

Legislation, too, can help better protect children, he says. "A lot of the agents that are used in manufacturing have never been looked at in relation to humans or children," Palfrey says. "We are pushing for more responsible legislation on the use and production of these chemicals."

"We need to study these chemicals first, and then try to put out things that have been proven to be relatively safe," he says. "We advocate for responsible studies before throwing something out into the environment."

Palfrey and others who support the overhaul of TCSA call on the companies who make chemicals to test them for safety instead of relying on the Environmental Protection Agency to prove they are unsafe, as is currently the case.

Improvement in Diagnosis of Childhood Cancer

Jeff Stier, a senior fellow at the conservative National Center for Public Policy Research, points out that the diagnosis of childhood cancer is improving, which could also account for the apparent increases.

"A generation ago we might not have known that these children had cancer [and] coincidentally this is the same time period that there are having been more chemicals," he says.

In addition, the chemicals being used today may be milder and less likely to cause harm than older broad spectrum pesticides and chemicals, he says.

"We now have a narrower spectrum of chemicals that kill only the pests or herbs that they are targeting, which is less harmful than dropping a big bomb alternative, so our exposure risk has declined as the number of chemicals has gone up," he says. "Many of the newer chemicals are replacing chemicals with a higher risk profile."

According to Stier, there is no good data to support the claims that environmental exposures to chemicals are causing an uptick in childhood cancers.